This application is for an Environmental Field Emission Analytical Scanning Electron Microscope (EFESEM). Recent advances in SEM technology open new opportunities for biomaterials research. The developments of field emission electron sources and environmental chambers allow high resolution imaging (down to 1 nm) of wet, oily, dirty, outgassing, low-atomic number and non-conductive samples in their natural state without sample modification or preparation. These capabilities are a breakthrough in the analysis of biomaterials and their performance that will constitute an integral part in the development of a new generation of biomaterials. The EFESEM is one of the most versatile instruments for microstructural characterization. When coupled with a multifunction x-ray analyzer, concurrent micro-chemical analysis is possible. This multiuser facility will greatly enhance the research of six NIH investigators. The SEM facilities available to LBNL, UCSF and UCB faculty at present are limited and much less capable. Funding is requested for the acquisition of a state-of-the-art environmental field emission SEM, a Hitachi 4300 SE/N. The proposal has received broad based support from departmental (LBNL, UCSF and UCB) faculty; personnel from laboratory groups representing six PI's with current funding from NIH are projected as users. The Proposed microscope will be housed at the National Center for Electron Microscopy (NCEM) at the Lawrence Berkeley National Laboratory (LBNL). NCEM is a world leader in the application of transmission electron microscopy to microstructural characterization which will guarantee maintenance and operation of the instrument at the top condition, and also excellent training and support for the users named on the grant proposal.